<!DOCTYPE html>
<!-- Any copyright is dedicated to the Public Domain.
   - http://creativecommons.org/publicdomain/zero/1.0/ -->
<head>
  <style>
    details::before {
      content: "This is the details.";
      /* Match the margins and display of <p> */
      display: block;
      margin-block-start: 1em;
      margin-block-end: 1em;
    }
  </style>
</head>
<html>
  <body>
    <details open>
      <summary>Summary</summary>
    </details>
  </body>
</html>
